Method of constructing roll shells



June 1, 1965 H. R. DOPP 3,186,063

METHOD OF CONSTRUCTING ROLL SHELLS Filed 001;. 2, 1961 3 Sheets-Sheet lI N VEN TOR. Homer Rea/yer 90 AT VORNEYS June 1, 1965 oPP METHOD OFCONSTRUGTING ROLL SHELLS S Sheets-Sheet 2 Filed Oct. 2, 1961 INVENTOR. bome -fiaer 00,0; BY a"? ORNEYS June 1, 1965 H. R. DOPP 3,186,063

METHOD OF CONSTRUCTING ROLL SHELLS Filed Oct. 2. 1961 3 Sheets-Sheet 3IN V EN TOR. flame od er 0% ATT( NEYS United States Patent METHOD OFCGNSIRUCTING RULE, SHELL$ Homer Rodger Dopp, 1835 Sherwood Drive,Beloit, Wis. Filed Oct. 2, 1961, Ser. No. 142,389 14 Claims. (Cl.29-14%.4)

This invention relates to improvements in roll shells and methods ofconstructing the shells.

Roll shells and particularly shells for the drier rolls and largediameter king or finishing rolls to be used in papermaking machinery arefrequently made by centrifugal casting, due to the resultant densehomogeneous castings free from air entrapment-s and porosity, and due tothe fact the centrifugal casting process produces an end product whichis dimensionally close to finished size so that little machining isrequired.

Such shells have been cast to maximum diameters of approximately 55inches, but at larger diameters the centrifugal casting process becomestoo complicated and expensive to be practical.

Roll shells of diameters in excess of 55 inches have been molded in aconventional manner by pouring the metal into the cylindrical spacebetween the mold and core and by prefabricating cylindrical sectionswhich have either been pre-cast or rolled out of metal plates, and

welding the sections together to the final cylindrical form.

In both of these prior methods the physical and mechanical properties ofthe centrifugal casting process are sacrificed and the resultant productis an inferior product over what could be obtained by centrifugalcasting. Also where the shell is constructed of prefabricated sections,the sections must be machined to obtain the required welding faces andgrooves, and it is not possible to maintain a uniform quality throughoutthe drum, thereby making it necessary to construct a heavier shell usingmore material than would be required with a centrifugal casting, inorder that the shell may stand up. Even then the resultant shell isstill subject to variationsin quality and is extremely difiicult toaccurately finish to a uniform size.

A principal object. of the present invention is to cure the foregoingdeficiencies in large diameter roll shells by providing a process forconstructing roll shells of large diameters, having the quality anduniformity of centrifugal cast bodies. 7

A further object of the invention is to construct a prefabricatedcylindrical body without losing any of the advantageouscharacteristicsand physical and mechanical properties normally obtained by thecentrifugal casting process. a

Still another object of the invention is to provide an improved methodof forming large diameter shells having the physical and mechanicalproperties of centrifugal cast shells, in which two shells of differentdiameters smaller than the diameter-of the finished shell are castcentrifugally and are then cut into sections, in which the radius ofeach section is increased to the required radius of the finished shell,and the sections are assembled and welded together.

A still further object of the invention is to provide an improved formof large diameter roll shell having the physical andmechanicalproperties of a centrifugally cast shell, in which the shell is formedfrom a plurality of centrifugally cast sections, cast at smallerdiameters than the diameter of the finished shell, and expanded to thediameter of the finished shell and welded together to the form of thedesired completed shell.

These and other objects of the invention will appear from time to timeas the following speecification proceeds and with reference to theaccampanying drawings where- FIGURE 1 is an end view of a centrifugallycast shell of one diameter;

FIGURE 2 is an end view of a second centrifugally cast shell of a largerdiameter;

FIGURE 3 is a fragmentary diagrammatic view showing one end portion ofone form of shell, chucked for cutting the shell longitudinally;

FIGURE 4 is an end view of a complete large diameter shell, showing thesections of two shells welded together after having been formed to therequired radius of the large diameter shell;

FIGURE 5 is a fragmentary side view of the shell shown in FIGURE 4;

FIGURE 6 is a diagrammatic sectional view of a fragment of a shellshowing the fragment of the shell within a sand mold, formed to form aweldinggroove in the shell, along which the shell may be cut; 7

FIGURE 7 is a diagrammatic fragmentary view of a fragment of a shell,showing the shell cut along the center of the welding groove; 7

FIGURE 8 is a diagrammatic sectional view taken through a section of ashell, showing the sections of the shell welded together;

FIGURE 9 is a perspective view of a large diameter finished shell,showing a modified form in which the shell may be fabricated;

FIGURE 10 is a view of small diameter centrifugally cast shell showingthe line of cutting of the shell, prior to expansion and assembly of theshell with another spirally cut and expanded shell;

FIGURE 11 is a perspective view of a small diameter spirally cutcentrifugally cast section of a shell expanded to the diameter of thefinished shell;

FIGURES 12 and 13 are side views of two shells of the same diameter, tobe cut in wedge shaped patterns and expanded and assembled to a largerdiameter shell;

FIGURE 14 is side view of a completed large diameter shell formed fromthe wedge shaped and expanded sections formed from the shells of FIGURES12 and 13;

FIGURE 15 is an enlarged fragmentary view illustrating the welding ofthe shell shown in FIGURE 14;

FIGURE 16 is a longitudinal sectional view taken through a completedroll showing a roll of a type used in a paper machine drier andillustrating the method in which the shell is mounted on the end headsof the roll; and

FIGURES 17 and 18 are fragmentary sectional views showing alternateforms for providing flanges on the ends of shells for bolting orotherwise mounting the shells to the end heads therefor, to form a drum.

In the embodiment of the invention illustrated in FIG- URES 1, 2, 3, 4and 5 of the drawings, I have shown a shell A of the radius R and ashell B of a radius R The shells A and B are centrifugally cast shellsand may be cast from bronze, iron or any other material commonly used inthe manufacture of paper machine rolls and roughly machined inside andoutside, if desired. Due to its high thermal c.onductivity,hbronze is apreferred material for rolls engaged by doctor blades for maintaining acoating to a predetermined thickness or for maintaining the surface ofthe roll clean.

The shell A is shown as being divided into sections 1, 2, 3 and 4. Theshell B is shown as being divided into sections 5, 6, 7, and 8. Theshells A and B are then cut along spaced radial dividing lines extendinglongitudinally of the two shells to form a plurality of shell sections.The shell sections are then each expanded to an increased radius in apress or like tool exerting pressure on the concave walls of thesections to form sections to conform to the diameter of the completedlarge diameter shell C,

.as shown in FIGURE 4. The centrifugally cast shell sections may then bebeveled along opposite sides thereof to form welding grooves when thesections are assembled.

The sections may then be assembled on a fixture and welded together tothe form shown in FIGURE 4.

In FIGURE 3 I have shown a method in which the .shells may be supportedprior'to cutting. As shown in this figure, the shells may becentrifugally cast to a greater length than the desired length of acompleted shell. They may then be mounted on chucks at their oppositeends engaging the base of the shell on end portions 11 of the shell,that will not be cut. The shell may then be longitudinally cut by sawingor burning as indicated by reference characters 12. The shell segmentsmay then be cut to length by sawing or burning inwardly of the ends ofthe shell, leaving the oversize end portions 11 of the shell in theircylindrical form. The oversize end portions 11 may be of a minimum widthequal to the thickness of the wall of the shell. A width of one and onehalf times the thickness of the wall of the shell is, however, desirablefor handling purposes.

Shell sections may also be formed by cutting or sawing slots along thelines 12, 12 in FIGURE 3 and by cutting the end portions 11 fromopposite ends of the shell. The shell sections may then be graduallyexpanded in a press or the like to the required radius of the completedshell.

'Other shell sections may be formed in the manner just described, andthe expanded shell sections so formed may then be assembled on a fixtureand welded together. It is, of course, obvious that the width of theslot may be selected to avoid waste.

The shell just described, formed by the method of the invention has thephysical and mechanical properties of centrifugally cast shells, and issuperior in quality to large diameter shells formed by ordinary sandcasting or by welding of sheet metal segments together, and is far moreeconomical and practical to manufacture than if a shell of the samediameter were manufactured by centrifugal casting processes.

In FIGURES 6, 7 and 8 I illustrate a manner in which welding grooves maybe formed along the adjacent edges of the assembled shell sectionsduring the centrifugal casting process. FIGURE 6 diagrammatically showsa fragment of a shell segment 15 in section and diagrammatically shows asection of a sand mold 16. The sand mold 16 has inwardly extendingarcuate ridges extending longitudinally therealong in registry with thelocations of the cuts required to sever the small diameter shells intosections. The ridges 17 form arcuate depressions or recesses 19 in thecentrifugally cast shell. The centrifugally cast shell may then be cutlongitudinally along the centers of the recesses 19, the recessedportions extending along the adjacent edges of the shell sections whenassembled, to form welding grooves. In FIGURE 8 two adjacent sectionsare shown as being welded together by welding material 21 in the moldedwelding grooves and are shown as being reinforced by a reinforcing plate22 extending along the inside of the welded joint.

It should here be understood that while I have described the roll asformed from centrifugally cast shells of diiferent diameters, they maybe formedfrom centrifugally cast shells of the same diameter, dependingupon the required diameter of the final shell. The shells are preferablymade from centrifugally cast cylinders of different diameters to providethe required material for a complete drum from two cylinders with nowaste, and where two cylinders of the same diameter may furnish thematerial for a complete shell, the two cylinders may be used.

In the modified form of the invention shown in FIG- URES 9, l0 and 11, acentrifugally cast shell 23 of a smaller diameter than the diameter ofthe completed shell is out along the helical lines indicated in FIGURE10. The shell sections are then opened and expanded to the requireddiameter of the completed shell. A second centrifugally cast shell ofthe same diameter as the shell 23 may then be cut along the same helicallines indicated in FIGURE 10 and opened to the diameter of the completedshell. The expanded shell sections will have opposite tapered endportions and widened intermediate portions and may then be assembled ona fixture with the tapered end portions extending from the widenedportions so the widened portion of one shell section will face thewidened portion of the next adjacent shell section and so the oppositeends of the assembled shell sections will be perpendicular to thecylindrical wall thereof. The assembled shell sections may then bewelded together to form a larger diameter shell 24.

While the cylinder shown in FIGURE 10 is shown as being cut along ahelix to open to a helix of the diameter of the completed shell, similarresults can be obtained by cutting along a part of a helix and thecylinders may be out along helixes of various desired pitches and thesections when assembled to the required diameter may be arranged in sideby side relation with respect to each other to form a cylinder of therequired length and diameter.

In this form of the invention a helical groove (not shown) along whichthe shell is to be cut may be cast in the shell in the form of a helicalU-shaped recess extending along the shell in the manner illustrated inFIGURE 6, to provide a welding groove when the shells are assembled forwelding.

A cylinder formed from welded centrifugally cast shell sections cutalong helixes and expanded, provides the uniform surface required forpaper machine rolls, in which the cylinders are in constant rollingcontact with each other. With such a shell the biting of the doctorblade in the roll, which may be caused by longitudinal ridges formed inthe surface of the shell, after wear, due to the difference in thematerial of the shell and the Welding material, is obviated.

In FIGURES 12 and 13, I have diagrammatically shown two shells 25 outinto tapered or wedge shaped sections after machining the inside of theshell. In this form of the invention the radii of the wedge shapedsections are increased to the inside radius of the completed shell. Theshell sections are then assembled in a fixture as shown in FIGURE 14,and welded along the juncture of the sections with each other to form alarge diameter shell 26.

FIGURE 15 illustrates the welding of the wedge shaped sections together.The welding grooves either may be machined on the wedge shaped sections,or may be formed by casting recesses along the lines of cutting of thesections as in FIGURES 6, 7 and 8.

In this form of shell, like the form of shell illustrated in FIGURE 9, adoctor blade or another roll working in conjunction with the shell willalways be in contact with a portion of the weld, with the result thatthe possibiliy of the doctor blade digging into the welds will bematerially reduced and the vibration caused by the welds where anotherroll works with the shell, will be eliminated.

In FIGURE 16 I have shown one manner in which a shell 30 may be mountedon end heads 31, to form a roll or drum for a paper machine drier, suchas is shown and described in Patent No. 3,089,252, which issued toRobert A. Daane and Edgar J. Justus on May 14, 1963. As shown in FIGURE16, a bolting ring 32, extends along the end and inner periphery of theshell 30 for a short portion of the length of the shell and is weldedthereto at 3% and 34. The head 31 may then be attached to the boltingring 32 as by cap screws or nuts and bolts.

In FIGURE 17 an annular bolting ring 35 extends inwardly of the marginof a shell 36 and is welded thereto at 37. The drum head-may then bebolted to the annular bolting ring 35.

In FIGURE 18 the bolting ring is L-shaped in cross section and has acylindrical portion 39 abutting the end of a cylindrical shell 49 and ofthe same diameter as the shell, andwelded thereto on the inner and outersides of the shell, as indicated by reference characters 41 and 42respectively. The cylindrical portion 39 has an inwardly extendingflanged portion 43 forming a bolting ring for bolting a head to theshell.

While I have herein shown and described several forms in which myinvention may be embodied, it may readily by understood that variationsand modifications in the invention may be attained Without departingfrom the spirit and scope of the novel concepts thereof as defined bythe claims appended hereto.

I claim as my invention:

1. The method of constructing large diameter roll shells which comprisesthe steps of casting two cylinders of smaller radii than the requiredradius of a finished shell, cutting each cylinder into at least oneshell section, in-

creasing the radii of the shell sections to the required radius of thefinished shell, and then welding the sections to the required radius.

2. The method of constructing roll shells which comprises the steps ofcasting two cylinders of smaller radii than the required radius of afinished shell, roughly machining the cylinders to size, cutting thecylinders into a plurality of shell sections, increasing the radii ofthe sections to the required radius of a finished shell, assembling theshell sections to the required diameter of the finished shell and thenwelding the sections together.

3. The method of constructing roll shells which comprises the steps ofcontrifugally casting two cylinders of smaller radii than the radius ofa finished shell, cutting the two cylinders into at least two shellsections, increasing the radii of the sections to the required radius ofthe finished shell and then assembling and welding the sections to therequired diameter.

4. The method of constructing roll shells which comprises the steps ofcontrifugally casting two cylinders of smaller radii than the radius ofa finished shell, cutting the cylinders longitudinally into a pluralityof sections, increasing the radii of the sections to the required radiusof the finished shell, assembling the sections into a cylindrical formand then welding the sections to the required diameter of the finishedshell.

5. The method of constructing roll shells which comprises the steps ofcentrifugally casting two cylinders of smaller diameters than therequired diameter of the finished shell, casting grooves in theperiphery of each cylinder during the casting operation, cutting the twocylinders along the centers of the grooves into at least two shellsections, increasing the radii of the sections to the required radius ofthe finished shell, then assembling the section-s to a cylindrical formand welding the sections together.

6. The method of constructing roll shells which comprises the steps ofcentrifugally casting a plurality of cylindrical shells of smallerdiameters than the required diameter of the finished shell and castingequally spaced grooves to extend along the periphery of each shellduring the casting operation, roughly machining the shells to size,cutting the shells along the centers of the grooves into a plurality ofsections, increasing the radii of the sections to the required radius ofthe finished shell, assembling the sections into a cylindrical form ofsubstantially the inside diameter of the finished shell, and thenwelding the sections along the adjacent grooved portions thereof, toform a shell of the required diameter.

7. In a method of constructing roll shells, the steps 6 of centrifugallycasting a plurality of cylinders'of smaller diameter than the requireddiameter of a finished shell and, longer than the length of a finishedshell, chucking the ends of the cylinders, longitudinally cutting thecylinders between the chucked ends thereof into sections of equal width,increasing the radii of the sections to the required radius of thefinished shell, assembling the sections to a cylindrical form of thediameter of the finished shell, and then welding the'sections together.

8. A method of constructing roll shells comprisingthe steps ofcentrifugally casting a plurality of cylinders of smaller diameters thanthe required diameter of the finished shell, cutting a slot in eachcylinder for the length thereof, expanding each slotted cylinder toshell sections having radii equal to the required radius of the finishedshell, assembling the expanded shell sections to a cylindrical form, andthen welding the sections together.

9. In a method of constructing roll shells, the steps of centrifugallycasting a plurality of cylinders of smaller diameters than the requireddiameter of a finished shell and longer than the length of a finishedshell, cutting a slot in each cylinder between the ends thereof, cuttingthe ends from each cylinder to form a plurality of shell sections,expanding each shell section to the required radius of the finishedshell, assembling the expanded shell sections to a cylindrical form, andthen welding the sections together.

10. In a method of constructing roll shells, the steps of centrifugallycasting a plurality of cylinders, machining at least the innerperipheries of the cylinders, severing each cylinder along helical pathsinto atleast two sections, expanding the severed sections to therequired inside radius of the finished shell, assembling the expandedspirally severed sections to form a cylindrical shell, and then weldingthe sections together.

11.' In a method of constructing roll shells, the steps of centrifugallycasting a plurality of cylinders and during casting thereof castinghelical grooves therein, severing each cylinder into at least twosections along the centers of the helical grooves, expanding the severedsections to the diameter of the finished shell, assembling the severedsections to form a cylinder having an inside diameter equal to therequired inside diameter of the finished shell, then welding thesections along the adjacent grooved portions thereof.

12. In a method of constructing roll shells, the steps of centritugallycasting a plurality of cylinders of the same diameter, machining atleast the insides of the cylinders to size, cutting the cylindersgenerally longitudinally thereof into a plurality of wedge shapedsections, increasing the radii of the sections so cut to the requiredradius of the finished shell, then assembling the sections cut into acylindrical shell having an inside diameter equal to the requireddiameter of the finished shell, and then welding the assembled sectionstogether.

13. In a method of constructing roll shells, the steps of centrifugallycasting a plurality of cylinders of the same diameter, having groovesformed in the outer peripheries thereof extending longitudinally thereofand angularly along the faces thereof to divide the cylinders into aplurality of wedge shaped sections, cutting the cylinders along thecenters of the grooved portions thereof to form a plurality of wedgeshaped sections, increasing the radii of the sections to the requiredradius of the finished shell, assembling the sections to the requireddiameter of the finished shell with the grooved portion of one sectionextending along the grooved portion of the other section, and thenwelding the sections along the grooved portions thereof.

14. The method of constructing roll shells which comprises the steps ofcentrifugally casting two cylinders of smaller diameters than thediameter of a finished shell,

cutting the two cylinders into at least two shell sections, expandingthe shell sections to conform to arcs struck Ifrom radii equal to theradius of the finished shell, beveling the shell sections along oppositesides thereof to form welding grooves when the sections are assembled,assembling the sections to form a cylinder having a diameter equal tothe diameter of the finished shell, and then Welding the sections alongthe welding grooves formed by the adjacent beveled sides of thesections.

References Cited by the Examiner UNITED STATES PATENTS Caas 138-154 XMeneely 138-154 X Zerbe.

Watson.

Hodge.

Shank 29-1484 X Carstens 29-463 WALTER A. SCHEEL, Primary Examiner.FRANK H. BRONAUGH, JOSEPH BEIN, Examiners.

1. THE METHOD OF CONSTRUCTING LARGE DIAMETER ROLL SHELLS WHICH COMPRISESTHE STEPS OF CASTING TWO CYLINDERS OF SMALLER RADII THAN THE REQUIREDRADIUS OF A FINISHED SHELL, CUTTING EACH CYLINDER INTO AT LEAST ON SHELLSCTION, INCREASING THE RADII OF THE SHELL SECTIONS TO THE REQUIREDRADIUS OF THE FINISHED SHELL, AND THEN WELDING THE SECTIONS TO THEREQUIRED RADIUS.